1. Field of the Invention
The invention relates to methods and devices for the detection of fuel gas leaks in a fuel cell system.
2. Description of the Related Art
Recently, attention has been given to fuel cells as a new energy source. The fuel cells generate electric power using oxygen and an appropriate fuel gas, such as hydrogen. A typical fuel cell system includes a fuel gas supply passage, a fuel gas discharge passage, and a gas circulation passage. Fuel gas is supplied to the fuel cell through the fuel gas supply passage. Fuel gas is discharged (purged) from a fuel electrode (hereinafter, referred to as “anode”) through the fuel gas discharge passage. The discharged fuel gas flows back to the fuel gas supply passage through the gas circulation passage. Hereinafter, the fuel gas supply passage, the fuel gas discharge passage, the gas circulation passage, and any other passages that the fuel gas may pass through, will be collectively referred to as “anode system passages”.
Technologies that can detect fuel gas leaks in the anode system passages are known. An example of such technology is disclosed in Japanese Patent Application Publication No. JP 2004-281132 A (hereinafter, referred to as “JP 2004-281132 A). In particular, JP 2004-281132 A describes the detection of a gas leak by comparing the amount of fuel gas flowing in the anode system passages detected by a hydrogen flow meter (HFM) or the like with the amount of fuel gas consumed by the fuel cell to generate electric power, the amount of fuel gas flowing from the anode system passages to an oxygen electrode through an electrolyte membrane of the fuel cell, and the amount of gas discharged (purged) through the fuel gas discharge passage.
That is, according to the disclosure of JP 2004-281132 A, a gas leak is detected by comparing the detected amount of fuel gas flowing in the anode system passages with the amount of fuel gas that 1) is consumed by the fuel cell to generate electric power, 2) flows from the anode system passages through an electrolyte membrane of the fuel cell to an oxygen electrode and 3) is discharged (purged) through the fuel gas discharge passage, as these are factors that cause the detected amount of fuel gas flowing in the anode system passages to fluctuate. However, the technology disclosed in JP 2004-281132 A does not take into account other factors that may cause the detected amount of fuel gas flowing in the anode system passages to fluctuate, which reduces gas leak detection accuracy.